1. Field of the Invention
The present invention relates to a structure of an ink jet recording device provided with a maintenance device for sucking ink drops, dust etc. stagnating in a recording head in order to recover from unsatisfactory ink jet using heat melting ink or ink which presents plastic-flowability at the ordinary temperature.
2. Description of the Background Art
An ink jet recording device of ink jet method where recording is performed by jetting ink drops from a plurality of ink jet outlets onto recording paper is widely used for a printer, facsimile, word processor etc. A recording head for the ink jet recording device includes those performing black-and-white printing and color printing which is adapted to accommodate ink of different colors. An example of a conventional jet recording device is disclosed, for example, in Japanese Patent Laying-Open No. 4-133750.
FIG. 7 is a schematic perspective view illustrating a structure of the ink recording device. A carriage 63 is provided such that carriage 63 can reciprocate along a guide shaft 61 by a driving belt 62. On carriage 63, a recording head 65 which is provided with an ink tank 64 is mounted. Recording head 65 performs printing on recording paper 67 which is carried to the front side of a platen roller 66.
A wiping blade 68 suitably abuts against recording head 65 and removes ink drops and dust adhering to recording head 65.
A cap 69 seals recording head 65 in a manner that head 65 is covered with cap 69 in order to protect head 65 when printing by head 65 is not performed, and sucks ink drops and dust stagnating in head 65 using a suction pump within a suction unit 71 which is connected to cap 69 via a suction pipe 70 when printing is unsatisfactorily performed. The ink drops and dust which are sucked by suction unit 71 are collected in waste ink unit 73. This recovers printing performance of recording head 65.
Now FIG. 8 is a schematic diagram illustrating the internal structure of suction unit 71. A suction pump 72, referred to as a tube pump, is provided in suction unit 71. A plurality of rollers 76a, 76b, 76c are rotatably attached to suction pump 72 around a rotor 75 which is driven by a motor. Each of rollers 76a, 76b, 76c can rotate about its center as a rotation axis.
A tube 78 which deforms elastically is provided between a pump case 72A and rotor 75. With rotor 75 rotating in the direction of the arrows shown in the figure, rollers 76a, 76b, 76c rotate while pressing against tube 78. This will generate negative pressure on the side of cap 69, and ink drops and dust are sucked from recording head 65 abutting against cap 69. The ink drops and other wastes sucked by suction pump 72 pass through from a tube 78a to a tube 78b, are sent to a waste ink unit 73 and collected there.
In the ink jet recording device described above, if ink within a nozzle of the recording head is mixed with air bubbles, dust, etc., ink jet at the recording head would be unsatisfactory. The unsatisfactory ink jet causes missing and displacement of printing dots. This causes the problem that quality of printing by the recording head will deteriorate.
In order to solve this problem, means have been taken for recovering printing performance of the recording head, by covering cap 69 with recording head 75 and sucking the recording head using a suction pump communicated with cap 69, so that air bubbles and dust can be sucked together with ink drops within recording head 75.
On the other hand, when heat melting ink is used for the ink jet recording device, high quality printing can be achieved, since the ink drops on recording paper bleed only to a small extent.
When heat melting ink is used in the ink jet recording device, the heat melting ink will be cooled and coagulate within the suction pipe while the head is being sucked if the head is sucked using a conventional suction unit. As a result, the suction pipe will be clogged and the ink drops cannot be sucked.
Furthermore, even if heat melting ink is sucked successfully, the heat melting ink which remains within the suction pump will be cooled and coagulate. As a result, the problem arises that the rotor and rollers within the suction pump will be stuck and that the suction pump cannot be used.
In other words, in the ink jet recording device using heat melting ink which is solid at the ordinary temperature and is heated for use, or ink which presents plastic-flowability at the ordinary temperature and is heated for use in printing, there has been a problem that the performance of the suction unit will deteriorate.